The present invention relates to a self-developing instant camera equipped with a motor-driven treating liquid spreader and more particularly to a safety shutter releasing system.
Generally, the consumption of electric power required for the self-developing instant camera is several times as much as that for more simple common cameras.
Also, the F stop value of the photographing lens used for such cameras is generally larger in view of the resolving power of the sensitive film material used. Accordingly in a self-developing camera having such a high F stop lens, the guide number reflecting strobe flash power needed is also required to be larger if a strobe is built into the camera, and, the electric power consumed for the strobe itself becomes larger. Assume that a photographer using such a camera has depressed the shutter button too soon after a previous picture while the built-in strobe is still recharging. A rush of current for operating the motor driving the treating liquid spreader will immediately be required from a battery which has dropped in voltage due to the drain of the recharging strobe. The full electric power may not be supplied to the motor. The film unit may jam in the treating apparatus rendering the camera inoperable.
Also, another accident related to battery power might occur. The shutter release might occur too soon after a previous picture, interrupting treatment of the previous film unit and its motorized delivery, i.e., while the end of the film unit is still located inside the film unit container. The subsequent film unit could become jammed between a transport member (the film unit is delivered up to the treatment spreader) and the film container (the film container is generally adapted to have such a construction so as to deliver only one film at a time to prevent the two-delivery operation), resulting in a motor stop accident.
In addition, if the film container has no two-delivery preventing wall, the premature delivery operation of a following film unit into the treatment spreader through a premature second releasing operation might cause the treatment spreader not to work sufficiently or two films may enter the same time, stopping the motor.
To prevent such accidents as described hereinabove, a release lock is proposed to render the shutter releasing system and the treating liquid spreader inoperative through detection of battery voltage, if the battery has been used, by a battery checker (see U.S. Pat. No. 3,417,683 Publication).